This invention relates to the field of advanced medical devices and particularly to intracorporeal devices for performing or aiding in the performance of therapeutic or diagnostic procedures. The intracorporeal devices may be guiding members such as guide wires for advancing intraluminal devices within body lumens. The intracorporeal medical devices include stent delivery catheters, balloon dilatation catheters, atherectomy catheters, electrophysiology catheters and the like.
In a typical percutaneous coronary procedure, a guiding catheter having a pre-formed distal tip is percutaneously introduced into a patient""s peripheral artery, e.g., femoral or brachial artery, by means of a conventional Seldinger technique and advanced therein until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guide wire is first advanced by itself through the guiding catheter until the distal tip of the guide wire extends beyond the arterial location where the procedure is to be performed. Then a catheter (which may be a rapid exchange type catheter such as described in U.S. Pat. No. 5,061,273 to Yock, or an over the wire catheter) is mounted onto the proximal portion of the guide wire which extends out of the proximal end of the guiding catheter which is outside of the patient. The catheter is advanced over the guide wire, while the position of the guide wire is fixed, until the operative element on the catheter is disposed within the arterial location where the procedure is to be performed. After the procedure is performed, the catheter may be withdrawn from the patient over the guide wire or the guide wire repositioned within the coronary anatomy for an additional procedure.
A guide wire may also be used in conjunction with the delivery of an intracoronary stent. One method and system involves disposing a compressed or otherwise small diameter stent about the distal end of a catheter, advancing the catheter through the patient""s vascular system over a guide wire until the stent is in the desired location within a blood vessel. The stent is then expanded within the blood vessel, holding the passageway thereof open. The stent may be self-expanding or expanded using an expandable device on the catheter such as a balloon, which after expanding is contracted and withdrawn from the blood vessel. This latter method and system can be used concurrently with balloon angioplasty or subsequent thereto.
Further details of guide wires, and devices associated therewith for various interventional procedures can be found in U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are hereby incorporated herein in their entirety by reference thereto.
Conventional guide wires for angioplasty, stent delivery, atherectomy and other intravascular procedures usually have an elongate core member with one or more segments near the distal end thereof which taper distally to smaller cross sections. A flexible body member, such as a helical coil or a tubular body of polymeric material, is typically disposed about and secured to at least part of the distal portion of the core member. A shaping member, which may be the distal extremity of the core member or a separate shaping ribbon which is secured to the distal extremity of the core member, extends through the flexible body and is secured to the distal end of the flexible body by soldering, brazing or welding, or an adhesive in the case of polymeric flexible bodies which forms a rounded distal tip. The leading tip is highly flexible and will not damage or perforate the vessel and the portion behind the distal tip is increasingly stiff which better supports a balloon catheter or similar device.
The shaping member or ribbon of a typical guide wire is a small diameter wire which has been flattened to a relatively constant transverse profile. However, the flattened proximal portion of the shaping member, which is usually attached to a flattened portion of the core member, provides an abrupt change in stiffness along its length which can lead to prolapse during use. Prolapse occurs when the shaping member becomes bent back on itself in a constrained lumen, and is difficult to straighten out with proximal manipulation. There is a need for a shaping member that avoids such prolapse. The present invention satisfies these and other needs.
The invention is generally directed to a medical device for performing or aiding in the performance of a therapeutic or diagnostic procedure. Specifically, the invention is directed to a guide wire for the introduction or advancement of a medical device into a patient for the performance of a therapeutic or diagnostic procedure.
The guide wire has an elongate core with a proximal core section and a distal core section, an elongated shaping element and a flexible body disposed about and secured to at least part of the distal core section. Preferably, at least part of the distal core section is provided with a surface, herein termed core paddle, which mates with and is preferably secured to a juxtaposed surface of the proximal portion of the shaping element. The elongated shaping element has a distal portion which is secured to the distal end of the flexible body. The portion of the shaping element distally adjacent to the juxtaposed core paddle and proximal portion of the shaping element has a bending stiffness between about 50% and about 150% of the bending stiffness of the two juxtaposed portions. Preferably, the bending stiffness of the distally adjacent portion of the shaping element is not less than about 80%, nor more than about 120% of the juxtaposed portions. Preferably, the bending stiffness of these two regions are essentially the same.
The proximal portion of the shaping element and the mating surface of the core paddle may be flat to ensure contact when secured together. They may be secured together in a suitable manner, e.g., by welding, brazing, soldering, adhesive bonding, mechanical connections and other known joining processes. The core paddle and the shaping element may be formed by coining, rolling or otherwise plastically deforming to a desired shape and dimensions.
The flexible body member disposed about the distal core section and the shaping element may take the form of one or more helical coils, polymer jacket, or the like. The distal end of the flexible body is secured to the distal end of the shaping element, an intermediate portion of the flexible body is preferably secured to the juxtaposed core paddle and the proximal portion of the shaping element.
The geometry and dimensions of the juxtaposed portions of the core paddle and the proximal portion of the shaping element and the geometry and dimensions of the shaping element distally adjacent to the juxtaposed portions may be modeled mathematically. While the preferred transverse shapes of the core paddle, the mating portion of the shaping element and the distally adjacent portion of the shaping element are rectangular, other specific transverse shapes may be selected in keeping with the principles of the invention to achieve specific usage requirements.
By providing matching bending stiffness at the shaping element-distal core section junction, the transition over the junction is smooth, so there is little chance for acute or abrupt buckling at the junction.
These and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying exemplary drawings.